The lateral response of single and group of piles under simultaneous vertical and lateral loads has been analyzed using a 3D finite element approach. The response in this assessment considered lateral pile displacement and lateral soil resistance and corresponding - curve. As a result, modified - curves for lateral single pile response were improved with respect to the influence of increasing axial load intensities. The improved plots can be used for lateral loaded pile design and to produce the group action design -multiplier curves and equations. The effect of load combination on the lateral pile group response was performed on three pile group configurations (i.e., 2×1, 2×2 and 3×2) with four pile spacings (i.e., = 2 , 4 , 6 and 8 ). As a result, design curves were developed and applied on the actual case studies and similar expected cases for assessment of pile group behavior using improved p-multiplier. A design equation was derived from predicted design curves to be used in the evaluation of the lateral pile group action taking into account the effect of axial load intensities. It was found that the group interaction effect led to reduced lateral resistance for the pile in the group relative to that for the single pile in case of pure lateral load. While, in case of simultaneous combined loads, large axial load intensities (i.e., more than 6 , where is lateral load values) will have an increase in -multiplier by approximately 100% and will consequently contribute to greater group piles capacities.